1. Field of the Invention
The present invention relates to an arrangement for load sharing in computer networks, and more exactly, an arrangement for distribution of traffic, for instance via Internet, from clients to the service suppliers who provide services from a multiple of servers. The invention makes possible distribution to a number of replicated servers. Suitable server is selected, for instance, on basis or available resources at the server""s interface or on less delay in the connection. The invention results in better performance and reduced traffic by distribution of the traffic geographically and from a resource point of view.
2. Discussion of the Background
Many internationally big companies provide a multiple of copies of their information servers, in some cases also abroad, with the aim to increase accessability and performance for the Internet user. One problem is that some servers always are more loaded than others, especially because audio- and video file transmissions in real time are becoming more and more popular. This results in congestions in the networks.
A conventional way of solving this problem is to replace an existing server by another which has higher process capacity and storage capacity. In most cases, however, the problem is not lack of capacity but lack of load sharing, i.e. the solution often is to utilize the existing network resources better.
In some cases the information is copied or replicated in a multiple of servers which are distributed geographically in different places in order to improve response times. Traditionally, the traffic is distributed on the different servers by using a sequential (round robin) or random technology. In this sequential technology the servers are selected sequentially in turn, whereas random technology selects servers in just any order. In none of these technologies information about the load on the servers, or of the localization of the servers in the network, is utilized.
The present invention solves the above mentioned problems by utilizing information about the load and the network topology of the servers, together with a technology to to address suitable servers, namely the anycast-technology (anycast routing and anycast addressing). By that, the invention can distribute traffic to geographically distributed servers so that the traffic is distributed to for instance less loaded server.
Consequently the present invention provides an arrangement for load sharing in a computer network, comprising a larger number of users or clients with computers, at least one service supplier which provides services via a number of replicated servers, a computer network with routers which can connect the client computers with the servers in order to connect a client computer which requests a service with suitable server.
According to the invention a number of replicated servers belong to a common address group (anycast-group) and each anycast-group is connected to a domain name server which has the ability to select one of the replicated servers, so that a router can establish a connection between the selected server and the service-requesting client computer.
Preferably the domain name server is arranged to select the least loaded replicated server or the nearest replicated server. Each replicated server can transmit a resource message which contains information about available resources at the server in question, and about the link parameters of the server.
Thanks to the new technology according to the present invention, a number of advantages are achieved. The end users make benefit from the lower delay and higher performance. The number of servers in the network or with the service supplier can be reduced. It will be easy to add or subtract servers without the users becoming interfered with, i.e. without interrupting services in progress. This implies considerably reduced investment costs and managing costs for the network operator and the service supplier, while the end laser at the same time is offered higher performance. The end users are not aware of that there are several servers which provide the same service.
The invention provides cost efficient solutions which can be configured automatically and are transparent to the user. The invention makes possible step by step expansion of servers and adapts the capacity according to the need. By routing traffic to the least loaded server, the number of jumps and potential time delays are reduced.